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Boiler brand guides

Grant Oil Boiler Guide

By Matthew Knight

Article 7 of 17

We take a close look at the the oil boilers manufactured by Grant boilers. Find out more about Grant oil boilers

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Grant is a Wiltshire-based boiler brand that has been designing, manufacturing and supplying heating products for more than 35 years. It says its core focus is to provide eco-friendly solutions to the problem of rising energy costs and CO2 emissions.

Grant is largely known for its oil boilers, but it is working towards making it easier for homeowners to integrate renewable energy components into their oil-fired home heating systems. Grant produces two main ranges of oil-fired boilers, the Vortex Pro and the Vortex Eco. Both come in a variety of specifications to give you flexibility over where they can be installed. 

The Vortex Pro combination boilers are available as both internal and external units in three heat outputs, suitable for small to medium homes. The Vortex Pro range of Kitchen/utility and external module boilers are available in nine different heat outputs to cater for all sizes of home. Most are heat-only and can be converted into system boilers, but some are available as system boiler variants.

Most of the Vortex Eco range are heat-only boilers but they can be changed into system boilers using a Grant conversion kit. The range includes wall-hung and floor-standing boilers in three heat outputs for small, medium and larger homes, with options for installing indoors, outdoors or in a utility room. 

You can find more details about the individual products in these ranges in our boiler reviews.

Boiler brand guide
Brand data for Vaillant boilers
Overall score M
Customer score
Engineer recommendation
Ease of sourcing parts
Table notes
The reliability and customer score are based on responses from a May and June 2019 survey of 8,458 boiler owners.
Engineer recommendation, build quality, availability of parts and spares, and ease of fixing a common fault and ease of servicing are based on responses to a June 2019 survey of 171 Which? Trusted Traders heating engineers.


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How much do Grant oil boilers cost?

Grant boilers cost between £1,180 and £2,380, depending on their size and type. 

Choosing the best Grant oil boilers

You can have a Grant oil boiler installed by a registered Grant boiler engineer. The best way to find an engineer is by getting in touch with Grant using the contact details below. 

Grant warranties and servicing

The heat exchanger on Grant Vortex Condensing Boilers is covered by a five-year guarantee. All other components of the boiler are guaranteed for two years from the date of purchase; they must be installed in accordance with the manufacturer’s instructions. 

Optional annual or three-year extended warranty schemes are also available. Installations can be registered online at the Grant website.

Grant parts and repairs

If a problem develops, contact your installer or commissioning engineer in the first instance to ensure that the fault is with the boiler, not any other heating system components.

In the first two years you must contact Grant Engineering (UK) Limited, which will arrange for the repair under the terms of its warranty. This is provided the boiler has been correctly installed and commissioned, serviced (if older than 12 months) and the fault is not due to tampering, running out of oil, freezing, or the failure of any external components not supplied by Grant UK.

Ask your installer to contact Grant, which will arrange for a qualified engineer to attend to the fault.

Grant service department 

01380 736920 

Grant contact details

Write to Grant at:

Grant Engineering (UK) Ltd.

Hopton House, Hopton Industrial Estate,



SN10 2EU

You can contact Grant by calling 01380 736 920.

Grant boiler customer service

01380 736920